When horseradish peroxidase is injected into the circumvallate papilla on the posterior rat tongue, a small, discrete group of motor neurons is labelled in the brainstem. These neurons are located just ventral to the taste projection of the glossopharyngeal nerve in the nucleus of the solitary tract. This nucleus is analogous to, and an extension of, the dorsal motor nucleus of the vagus nerve; therefore, it is termed the dorsal motor glossopharyngeal nucleus. The objective of the proposed pilot, feasibility studies is to test the hypothesis that this nucleus projects to and controls secretion of the von Ebner's glands. The von Ebner's glands are minor salivary glands located beneath the circumvallate papilla, which have received little systematic investigation. Horseradish peroxidase will be injected into the dorsal motor glossopharygeal nucleus and the circumvallate papilla and von Ebner's glands subsequently examined for reaction product. Also, the nucleus will be electrically stimulated to determine whether this elicits secretion by the glands. These studies will identify the motor neurons controlling secretion of one set of salivary glands and will provide the basis for a comprehensive study to clarify the reflex control of salivation via taste stimuli.